... Herschel telescope detects water on dwarf planet . Scientists have made the first definitive detection of water vapor on the asteroid Ceres. ... Ceres is classified as a dwarf planet, a solar system body bigger than a typical asteroid and smaller than a planet. ... This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere, said Michael K ppers of ESA in Spain. ...